Wikipedia
Chandrashala
Chandrashala is the term most often used to describe the circular or horseshoe arch that decorates so many Indian cave temples and shrines. The arch is shaped like the cross-section of a barrel vault. When used on the facade of a chaitya hall, it is called a chaitya arch. It is sometimes called a gavaksha (or kudu, in Tamil) when used as a decorative element on a structural temple.
Examples include Ellora Caves 10, Ajanta Caves 9 and 19 and Varaha Cave Temple at Mamallapuram.